I Corinthians 7:3-7

Let the husband render to his wife the affection due her, and likewise also the wife to her husband. The wife does not have authority over her own body, but the husband does. And likewise the husband does not have authority over his own body, but the wife does. Do not deprive one another except with consent for a time, that you may give yourselves to fasting and prayer; and come together again so that Satan does not tempt you because of your lack of self-control. But I say this as a concession, not as a commandment. For I wish that all men were even as I myself. But each one has his own gift from God, one in this manner and another in that.